“Even though it’s really hard and miserable, and you resolve you’re not going to ever do it again, you reach the top,” says Andersen, 66, of Medford.

And then you hike down, and the misery melts into an elation no one ever feels sitting on a sofa.

“I call it the after-glow,” Andersen says. “It can last for days, weeks, months, even years. That realization that you did something really hard but really worth doing.”

Andersen is planning again to share that after-glow with a dozen or more hikers the last weekend in June, when he continues his nearly annual tradition of leading a hiking group up Mount Shasta.

If summiting the 14,179-foot volcano is on your bucket list this early summer, now is the time to get in shape to tackle it, he says.

Andersen prefers to ride his road cycle and mountain bike up places like Andersen Butte and Griffin Lane regularly to gain the cardiovascular capacity and leg strength to power up the mountain and back in one long, grueling yet exhilarating day, he says.

Others run countless road miles, while still others will climb Mount McLoughlin and mix in hours on stairclimbers in urban gyms.

Regardless of how you get there, Andersen says there’s a basic rule of thumb he tells prospective hikers to gauge whether their idea of being in good shape is good enough to tackle Shasta.

“If you can run 10 miles without stopping or if you can cycle 30 miles while doing some climbing and descents, then you’re probably ready,” Andersen says. “But I’ve seen others who can’t do either of those make it. The big part is the mental. Keep repeating the mantra, ‘I won’t give up.’ ”

Mount Shasta is the second-highest peak in the Cascades, a potentially active volcano that last erupted more than 200 years ago. It is mostly within the Mount Shasta Wilderness Area, sports glaciers, and it challenges hikers with a mix of snow, ice and unstable scree that can lead to poor footing and some falls.

There is no actual trail to the summit, but climbers use several routes, and all include cross-country travel.

The main climbing season typically runs late April into August, when anywhere from 6,000 to 9,000 people attempt the ascent and roughly half of them make it, says Andrew Kiefer, a climbing ranger and avalanche forecaster for the Mount Shasta Ranger Station of the Shasta-Trinity National Forest.

Most people who try it are in fairly good shape, but any combination of weather and hiking conditions such as wind join fitness issues is forcing people to turn back, Kiefer says.

Regardless, Shasta clearly isn’t something you climb by rising off the sofa, brushing potato chips off your chest and grabbing your crampons and ice ax on your way out the door.

Andersen is a mountain climber who has tackled peaks ranging from Mount Hood and Mount Ranier, as well as Southern California’s Mount Whitney and even Tanzania’s Mount Kilimanjaro. He first hiked Mount Shasta in 1999 with his eldest son and has returned almost annually to what he calls “a very respectable mountain to climb.”

He started leading small groups of hikers on his regular treks a few years later, usually leaving from the Bunny Flat Trailhead, which lies at 6,950-feet elevation on the south side of the mountain. The climbers begin their trek at 12:30 a.m. for an ascent that can last as long as 12 hours depending upon the makeup of the group, Andersen says.

Andersen says he typically takes two liters of water, then refills and heavily hydrates at Horse Camp, a Sierra Club property 7,884 feet up the mountain. He carries two liters for the final ascent, with snacks such as boiled eggs, power bars and beef jerky to help offset the roughly 15,000 calories burned that day.

Andersen prefers hiking the west-face route which, while it blocks the morning sunrise, does offer a rare opportunity to view an “alpenglow,” Andersen says.

That’s when a ribbon of purple-red light glows in the western sky behind the mountain’s shadow, he says.

“Every year somebody will notice it, and we’ll all stop and look at it,” Andersen says.

While the mental fight up the mountain can be mesmerizing, Andersen says he and his group often stop to take in the views. He carries a cellphone for photos and wears a GoPro on his chest for videos.

They often lounge a bit at the summit and usually take the more popular Avalanche Gulch route back to reality.

The hiking groups have evolved over time from just friends to “friends of friends” who eventually become the former.

Last year’s group of 14 hikers fared better than average for Mount Shasta, with all but four making it to the summit, Andersen says. Three bowed out because of exhaustion and trouble with the altitude adjustment, while the fourth had “boot issues” that undermined his attempt, Andersen says.

Some years the hikers will splinter into faster- and slower-paced groups, he says. Last year, however, they all stuck together.

“Everyone was willing to go the pace that the slowest person could go,” Andersen says. “Ten came home with the after-glow.”

Reach Mail Tribune reporter Mark Freeman at 541-776-4470 or mfreeman@rosebudmedia.com. Follow him on Twitter at www.twitter.com/MTwriterFreeman.